Perhaps it starts with his laugh, a device he employs at odd moments and in a most peculiar way. (The public thinks that crying is the acid test of the actor, but in fact “laughing” is much harder — and Mr. Romney hasn’t mastered it.)

Listen to his laugh. It resembles the flat “Ha! Ha! Ha!” that appears in comic-strip dialogue balloons. But worse – far worse – it is mirthless. Mr. Romney expects us to be amused, although he himself is not amused. Freeze the frame, cover the bottom of his face with your hand, and study his eyes. There’s no pleasure there, no amusement.

As the Obama campaign this week began a concerted attack on the presumptive GOP nominee for his tenure at the private equity firm he managed, strategists in both parties say the Republican has yet to give a confident, detailed explanation of his Bain Capital tenure that silences questions about his biography as a businessman.